The most common way to fasten a sanitary napkin inside a pair of underpants during use has up to now been to arrange a fastening surface in the form of pressure-sensitive adhesive on the side of the napkin which during use is intended to be in contact with the underpants of the user. In order to avoid adhesion problems with the adhesive surface during storage and transport of the napkins, the fastening adhesive is usually protected with a special removeable strip of material made of release agent treated paper, or similar. When the napkin is to be used, the protective strip is removed, so that the adhesive is exposed and can be used for fastening of the napkin in the underpants of the user. The protective strip does not have any further function, but is thrown away after it has been released from the fastening adhesive. The use of such protective strips has a number of disadvantages. For example, it is awkward to handle the protective strips when the sanitary napkin is to be used, especially if the sanitary napkin is provided with several different protective strips which have to be removed. Furthermore, the use of protective strips results in the use of unnecessarily large amounts of material, which is a disadvantage from an environmental and energy point of view, as well as with respect to costs.
In order to eliminate the special protective strips, it is known to provide a sanitary napkin with adhesive regions as well as release agent treated regions arranged in such a way that the sanitary napkin can be folded together with the adhesive regions in contact with and protected by the release agent treated regions. Such sanitary napkins are described in U.S. Pat. No. 4,376,440, EP 471,384, EP 471,385, EP 471,386 and EP 471,387.
Such an arrangement brings about a reduction in material consumption as well as certain simplifications in handling the sanitary napkin. A principal problem and a big disadvantage with it is, however, that the possibility of applying the fastening adhesive in the way which gives the best anchoring of the sanitary napkin inside the user's underpants, is greatly limited, since the placing of the adhesive surface primarily must be chosen so that the adhesive surface after folding together of the sanitary napkin lies in contact with the corresponding release agent treated area.
From EP 393,953 a pressure sensitive adhesive fastening device is known, which comprises a carrier of which one side is equipped with a pressure sensitive adhesive, arranged in the spaces between a series of pegs or projections, projecting out from the carrier, wherein the pegs or projections extend out beyond the adhesive. The fastening device is especially suitable for use on cloth, whereby the pegs or projections are able to penetrate the surface of the cloth so that the adhesive is brought into contact with, and adheres to, the cloth. The problems with such a known fastening means are that they are relatively expensive and complicated to manufacture, and further that they are stiff and hard and for this reason easily cause chafing or other discomfort to the user. Furthermore, the projecting tabs involve a certain risk of damage to the surface which the arrangement is fastened to. A similar adhesive fastening device is described in U.S. Pat. No. 4,376,440.
U.S. Pat. No. 4,336,804 and U.S. Pat. No. 4,337,772 describe sanitary napkins with fastening devices made of a combination of parts with sticky adhesive and parts with non-sticky adhesive. The non-sticky adhesive is thereby arranged so that its surface which is facing away from the sanitary napkin is located at a greater distance from the napkin than the corresponding surface on the sticky adhesive. Such an arrangement of adhesive is, however, comparatively complicated to manufacture, as it requires two adhesive applicators which must be synchronized. This naturally also means that the manufacturing of the known sanitary napkins becomes unnecessarily expensive.
A further sanitary napkin with an adhesive fastening device is described in EP 234,194 and EP 229,639. This known sanitary napkin comprises a pressure sensitive fastening adhesive layer, as well as an elastic foam material layer applied on the outside of the adhesive layer and provided with openings through which the adhesive is exposed for fastening. Such a fastening device has not a sufficiently large available fastening area so as to be able to achieve a satisfactory fastening. Furthermore, there are difficulties during manufacture of the a known sanitary napkin, as a web of foam material is relatively fragile and easily breaks when it is subjected to the tensile forces which occur during high production speeds. Furthermore, at high production speeds, it is hard to control and regulate the stretching which occurs in the elastic foam material. Furthermore, the foam material is expensive and difficult to manufacture in the form of a sufficiently thin layer to enable the adhesive to be effective through the foam layer. Furthermore, a thick bulky material is difficult to handle in a continuous process, as it requires frequent roll changes, which naturally negatively influence the effectivity and cost.
A further problem with the earlier known sanitary napkins with a fastening means in the form of a coating of pressure sensitive adhesive, is that it is difficult to control the degree of adhesion, so that it is sufficiently great, irrespective of which type of material the underpants of the user are made of. The adhesive capacitity is of different strength for different textile materials and one and the same adhesive coating can fasten many times better on a surface of nylon, or nylon-type material than on a material of cotton. In the case of an adhesive coating which gives sufficiently good fastening in underpants made of cotton, there is the risk that a pair of underpants made of nylon or similar are damaged when the napkin is removed, or that traces of adhesive remain in the underpants.
Diapers of the type described in the introduction have up to now been fastened together by means of tape tabs which are fastened against a reinforced plastic surface on the front part of the diaper. Even if such a fastening system offers a satisfactory fastening of the diaper, it is still, however, connected with certain disadvantages. For example, it is complicated to protect the tape tabs before use. This is solved on the known diapers by folding the tabs in towards release agent treated surfaces either on the tabs themselves, or on the diaper. Folded tabs are expensive and complicated to manufacture and apply to the diapers and are the cause of a relatively large amount of the waste which occurs when the diapers are manufactured. Furthermore, it can be hard to pick the tape free from the release agent treated surface when the diaper is to be used. Especially when applying the diaper to a very lively child, difficulty in opening the tabs can be irritating. In order to increase the ease of handling of the tape tabs, these are manufactured from fairly stiff material which can easily produce sharp corners and edges which may cause chafing and irritation to the user's skin.